ARM: take care not to set the ThumbFunc bit on TLS data symbols

This fixes LNT SingleSource/UnitTests/Threads with -mthumb.

Differential Revision: http://reviews.llvm.org/D4324


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212029 91177308-0d34-0410-b5e6-96231b3b80d8